Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Neuroleptic drugs have been shown to affect the level and messenger ribonucleic acid of specific neuropeptides. The effect of subchronically administered neuroleptics on neuropeptide metabolism, however, has not been systematically characterized. In the present study, the effect of neuroleptics and other dopaminergic compounds on substance P (SP), cholecystokinin and met-enkephalin degradation was determined on intact, regional, rat brain slices. After 7-day administration of haloperidol (1 mg/kg) or chlorpromazine (20 mg/kg), SP degradation was decreased in caudate-putamen and nucleus accumbens. After administration of the dopaminergic agonist apomorphine (5 mg/kg, b.i.d.), SP degradation was increased in the nucleus accumbens. The dopamine D2-receptor antagonist sulpiride (100 mg/kg, b.i.d.) produced no effect on SP degradation. Met-enkephalin degradation was decreased after haloperidol administration in both frontal cortex and caudate-putamen and unaffected by apomorphine administration. The metabolism of cholecystokinin was not affected by neuroleptic treatment. Studies performed with specific peptidase inhibitors suggested that neutral endopeptidase 24.11, metalloendopeptidase 24.15 and aminopeptidases degrade SP on caudate-putamen and nucleus accumbens slices. Therefore, alterations in these peptidases may be responsible for the change noted in SP degradation after dopaminergic compound administration. These metabolic changes noted after neuroleptic administration may therefore contribute to neuroleptic-induced alterations in regional peptide levels.
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PMID:Neuropeptide metabolism on intact, regional brain slices: effect of dopaminergic agents on substance P, cholecystokinin and Met-enkephalin degradation. 754 72

The DNAs encoding three melanocortin receptor subtypes (melanocortin MC1 receptor, melanocortin MC3 receptor and melanocortin MC5 receptor) were expressed individually in COS (CV-1 Origin, SV40) cells to characterise their ligand binding properties. The results indicated that [125I][Nle4, D-Phe7]alpha-MSH (melanocyte stimulating hormone) bound to a single saturable site with Kd values of 85.1 +/- 8.0 pmol/l (mean +/- S.E.M), 396 +/- 65 pmol/l and 5.05 +/- 1.00 nmol/l for melanocortin MC1 receptor, melanocortin MC3 receptor and melanocortin MC3 receptor, respectively. The melanocortin MC1 receptor and the melanocortin MC5 receptor showed a similar potency order to the melanocortic peptides examined which was markedly different from the potency order of the melanocortin MC3 receptor. The melanocortin MC1 receptor and melanocortin MC5 receptor had a relatively higher affinity for alpha-MSH than gamma-MSH and beta-MSH, whereas the melanocortin MC3 receptor had higher affinity for desacetyl-alpha-MSH, gamma-MSH and beta-MSH compared to alpha-MSH. The inclusion of the endopeptidase inhibitor phosphoramidon to prevent the breakdown of ACTH-(1-39) (adrenocorticotrophic hormone) to alpha-MSH, decreased ACTH-(1-39) binding affinity showing that ACTH-(1-39) had a much lower affinity for melanocortin MC1 receptor than reported earlier.
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PMID:Characterisation of melanocortin receptor subtypes by radioligand binding analysis. 777 75

LLC-PK1 cells were transfected with a cDNA encoding rabbit neutral endopeptidase (NEP; EC 3.4.24.11), an abundant enzyme of the kidney proximal brush border. Clones of cells expressing high levels of the protein were isolated. Selective biotinylation and radioimmunolabelling were used to determine that 85-95% of NEP was localized in the apical domain of filter-grown LLC-PK1 cells. Pulse-chase and selective biotinylation studies revealed that the majority (85%) of newly made NEP was directly targeted to the apical membrane. However, a soluble form of NEP was found to be secreted in approximately equal amounts from both sides of the monolayer when expressed in LLC-PK1 cells. Transfected pro-opiomelanocortin, a pituitary hormone precursor, was secreted almost exclusively into the basolateral medium, suggesting that the bulk flow is to the basolateral membrane. This behaviour contrasts with that observed in MDCK cells, where both the transmembrane and secreted forms of NEP are directly targeted to the apical membrane and where the secretion of pro-opiomelanocortin is unpolarized.
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PMID:Direct targeting of neutral endopeptidase (EC 3.4.24.11) to the apical cell surface of transfected LLC-PK1 cells and unpolarized secretion of its soluble form. 782 24

Neutral endopeptidase (EC 3.4.24.11, NEP) is a type-II integral membrane protein found in a wide variety of cell types. We previously produced a secreted form of the enzyme by deletion of the cytoplasmic and transmembrane domains and in-frame fusion of the cleavable signal peptide of pro-opiomelanocortin [Lemay, Waksman, Roques, Crine and Boileau (1989) J. Biol. Chem. 264, 15620-15623]. Here we have used this secreted form of NEP and fused to it the glycosylphosphatidylinositol (GPI)-anchor attachment signal of decay-accelerating factor to produce a GPI-anchored form. Expression of this chimeric form in Cos-1 cells resulted in cell-surface activity. This activity could be released from the cell surface by phosphatidylinositol-specific phospholipase C and radiolabelling studies showed that the protein could incorporate [3H]ethanolamine, indicating that the enzyme was GPI-anchored. The Km value, using [D-Ala2,Leu5]enkephalin as substrate, of GPI-anchored NEP (62 +/- 5 microM) was comparable with that of wild-type NEP (70 +/- 4 microM), as were the sensitivities to the inhibitors phosphoramidon and thiorphan. However, pulse-chase studies showed that the biosynthesis and cell-surface delivery of GPI-anchored NEP was delayed compared with that of the wild-type transmembrane form of NEP. These results suggest a lower rate of biosynthesis and/or cellular transport for GPI-anchored NEP compared with its transmembrane counterpart.
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PMID:Expression of an enzymically active glycosylphosphatidylinositol-anchored form of neutral endopeptidase (EC 3.4.24.11) in Cos-1 cells. 816 36

A lysed preparation of isolated insulin secretory granules efficiently cleaved murine proopiomelanocortin (mPOMC) at physiologically important Lys-Arg processing sites. This processing was mostly attributed to an activity that co-eluted with the proinsulin processing type-II endopeptidase from anion exchange chromatography (Lys-Arg-directed; Davidson, H. W., Rhodes, C. J., and Hutton, J. C. (1988) Nature 333, 93-96). The principal peptide hormone products generated by the insulin secretory granule lysate were identified by specific radioimmunoassay and NH2-terminal microsequencing analysis of high performance liquid chromatography-separated products as alpha-melanocyte-stimulating hormone, corticotropin-like intermediate, gamma-lipotropin, beta-endorphin-(1-31), 18-kDa NH2-terminal fragment and, to a lesser extent, adrenocorticotrophin and beta-lipotropin. This processing had an acidic pH optimum (pH 5-5.5) and was Ca(2+)-dependent (K0.5 activation = 5-80 microM). With increasing Ca2+ concentrations there was an increase in the extent to which mPOMC was processed. The in vitro processing of mPOMC by the insulin secretory granule endopeptidase activity reported here is in excellent agreement with the in vivo processing of this prohormone by a combination of PC2 and PC3, candidates of prohormone endpeptidase, in gene transfer studies with cells that express the regulated secretory pathway (Thomas, L., Leduc, R., Thorne, B. A., Smeekens, S. S., Steiner, D. F., and Thomas, G. (1991) Proc. Natl. Acad. Sci. U.S.A. 88, 5297-5301).
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PMID:Processing of proopiomelanocortin by insulin secretory granule proinsulin processing endopeptidases. 838 98

Cardiopulmonary bypass (CPB) results in a diffuse inflammatory response characterized in part by hyperstimulation of leukocytes. We have previously shown that this hyperstimulation appears to be due, in part, to an increase in the release of biological response modifiers (BRMs) such as cytokines. In the present study, we evaluated the ability of a naturally occurring immunocyte inhibitory substance, alpha-melanocyte-stimulating hormone (alpha-MSH), to prevent the hyperstimulation caused by CPB. Monocytes and granulocytes were pretreated with alpha-MSH (10(-6) M) before exposing the cells to plasma obtained from patients who had undergone CPB, as CPB plasma would stimulate native monocytes and granulocytes in a manner similar to that observed in CPB patients. Pretreatment of these cells with alpha-MSH significantly diminished the hyperstimulation induced by CPB plasma in a concentration-dependent manner. In contrast, when the cells were first or simultaneously exposed to CPB plasma and then to alpha-MSH, alpha-MSH had no effect. Furthermore, use of the specific neutral endopeptidase inhibitor, phosphoramidon, significantly increased the efficacy of alpha-MSH in inhibiting CPB-induced immunocyte activation. The data demonstrate that pretreatment of monocyte/macrophages and granulocytes with alpha-MSH effectively inhibits the immune hyperstimulation induced by CPB-plasma exposure. In addition, the data strongly suggest that preexposure to other naturally occurring immune inhibitory substances may diminish the hyperstimulation associated with CPB. The study also further confirms that this hyperstimulation may, in part, be due to BRMs released from immunocytes.
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PMID:Hyperstimulation of leukocytes by plasma from cardiopulmonary bypass patients is diminished by alpha-MSH pretreatment. 879 93

The immunocyte behavior (conformational changes and locomotion in response to signal molecule challenge) in patients about to undergo elective cardiac surgery was studied to elucidate the effect of psychological anticipatory stress on the immune system. Granulocytes and monocytes from 10 patients and 35 non-surgical controls were examined. Computer-assisted microscopic image analysis, capable of measuring cellular conformational and velocity changes, was used to measure the responsiveness of these immunocytes to peptidergic and cytokine stimulation. Immunocyte desensitization would appear to account for the reduction in their abilities to respond to chemotaxic challenge associated with the pre-cardiac surgery state. Their abilities to respond to D-Ala2-Met-enkephalinamide (DAMA) were observed only at much higher concentrations than previously reported (10-11 M vs. 10-9 M prior to surgery). This finding, together with the observed decrease in adrenocorticotropin levels compared to non-surgical controls, suggests that neutral endopeptidase activity was elevated just prior to surgery. Indeed, neutral endopeptidase activity is statistically elevated in the pre-cardiac surgery state. Furthermore, glucocorticoid levels remained constant, within normal resting limits, in both groups. Thus, surgical anticipatory stress may manifest itself, in part, as a desensitization of various immunocytes. Thus, a psychological anticipatory stress response may be a precipitant of the desensitization. Although this desensitization seemed not to involve the entire hypothalamic-pituitary-adrenal axis, the data suggest that psychological anticipatory stress may initially involve and influence autoimmunoregulation.
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PMID:Surgical anticipatory stress manifests itself in immunocyte desensitization: evidence for autoimmunoregulatory involvement. 879 95

A neutral endopeptidase (NEP) from Lactococcus lactis has recently been cloned and shown to contain high sequence homology with the human neutral endopeptidase, endopeptidase 24.11 (I. Mierau et al., J. Bacteriol. 175, 2087-2096, 1993). The gene for the neutral endopeptidase from L. lactis was cloned into the pQE expression vector, resulting in the fusion of a hexahistidine at the N-terminus. The recombinant enzyme was expressed to high levels in Escherichia coli (approximately 10 mg/liter of culture) and purified to homogeneity in a two-step procedure. A number of peptides were studied as substrates for the enzyme. The enzyme cleaves the following peptides at the Gly3-Phe4 bond: enkephalins, dynorphins A-6, A-8, A-9, A-10, A-13, and A-17, and alpha-neo-endorphin. In addition the enzyme hydrolyzes bradykinin, substance P, beta-endorphin, ACTH, and VIP. Although the cleavage patterns observed are similar to that seen with mammalian neutral endopeptidase, the lactococcal enzyme more efficiently cleaves larger peptide substrates. As observed with the mammalian neutral endopeptidase, the lactococcal enzyme exhibits higher kcat/K(m) values for the enkephalins than for their corresponding amides, indicating the functionality of an active-site arginine. Inactivation of the lactococcal endopeptidase by diethyl pyrocarbonate and protection afforded by the substrate dynorphin A-6 indicate the functionality of a positionally conserved active-site histidine. This was confirmed by demonstrating that conversion of this histidine, histidine 587, to glutamine generated inactive enzyme. Similarly, conversion of the putative zinc ligand glutamate 535 to glutamine led to inactive enzyme. These studies indicate a conservation of critical catalytic residues between the two enzymes and suggest that the lactococcal endopeptidase is a better model than thermolysin for the mammalian enzyme.
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PMID:Heterologous expression and characterization of recombinant Lactococcus lactis neutral endopeptidase (neprilysin). 880 62

The aim of the present study was to investigate some putative neurotransmitters involved in nociception and pain in parturients during active labour experiencing intense visceral pain. The concentration of the excitatory amino acid aspartate was significantly increased, and there was a tendency for an increase in glutamate, in lumbar cerebrospinal fluid (CSF) of parturients in active vaginal labour compared with control patients without pain subjected to elective caesarean section. The CSF concentration of the nitric oxide breakdown product nitrate was significantly decreased in parturients compared with control patients and healthy volunteers. No significant differences in the concentrations of substance P, substance P-endopeptidase or met-enkephalin were detected between parturients and controls. Our data suggest a paradoxical negative relationship between CSF concentrations of excitatory amino acids and nitric oxide in labour pain. The mechanisms behind this finding is unclear at present.
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PMID:Increased cerebrospinal fluid concentration of aspartate but decreased concentration of nitric oxide breakdown products in women experiencing visceral pain during active labour. 914 Oct 79

Human obesity has an inherited component, but in contrast to rodent obesity, precise genetic defects have yet to be defined. A mutation of carboxypeptidase E (CPE), an enzyme active in the processing and sorting of prohormones, causes obesity in the fat/fat mouse. We have previously described a women with extreme childhood obesity (Fig. 1), abnormal glucose homeostasis, hypogonadotrophic hypogonadism, hypocortisolism and elevated plasma proinsulin and pro-opiomelanocortin (POMC) concentrations but a very low insulin level, suggestive of a defective prohormone processing by the endopeptidase, prohormone convertase 1 (PC1; ref. 4). We now report this proband to be a compound heterozygote for mutations in PC1. Gly-->Arg483 prevents processing of proPC1 and leads to its retention in the endoplasmic reticulum (ER). A-->C+4 of the intro-5 donor splice site causes skipping of exon 5 leading to loss of 26 residues, a frameshift and creation of a premature stop codon within the catalytic domain. PC1 acts proximally to CPE in the pathway of post-translational processing of prohormones and neuropeptides. In view of the similarity between the proband and the fat/fat mouse phenotype, we infer that molecular defects in prohormone conversion may represent a generic mechanism for obesity, common to humans and rodents.
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PMID:Obesity and impaired prohormone processing associated with mutations in the human prohormone convertase 1 gene. 920 82


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